• Honam Mathematical Journal
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• v.40 no.4
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• pp.785-794
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• 2018

In [8] they introduced a new finite element method for accurate numerical solutions of Poisson equations with corner singularities. They consider the Poisson equations with homogeneous Dirichlet boundary condition with one corner singularity at the origin, and compute the finite element solution using standard FEM and use the extraction formula to compute the stress intensity factor, then pose a PDE with a regular solution by imposing the nonhomogeneous boundary condition using the computed stress intensity factor, which converges with optimal speed. From the solution they could get an accurate solution just by adding the singular part. This approach uses the polar coordinate and the cut-off function to control the singularity and the boundary condition. In this paper we consider Poisson equations with multiple singular points, which involves different cut-off functions which might overlaps together and shows the way of cording in FreeFEM++ to control the singular functions and cut-off functions with numerical experiments.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2002.03a
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• pp.3-11
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• 2002

Source parameters for forty nine recent earthquakes occurred in and around Korean Peninsula are determined and the relations among them are studied. The corner frequency and seismic moment are estimated from three different methods. The spectral fitting of the source displacement spectrum with the $\omega$-square source model of Brune(1970) and Snoke(1987)'s method are applied to all events and empirical Green's function method for two events are adopted. The source parameters determined in this study show different values depending on the adopted method and on the stations of which seismograms are recorded. It is interpreted that the disagreements principally originate from insufficient consideration of source radiation pattern and attenuation and amplification according to path direction. The corner frequencies and seismic moments are averaged to exclude the directional effects and other source parameters are estimated from the mean corner frequency and seismic moment. The static stress drops estimated in this study tend to be independent of seismic moment or magnitude for events above a certain size. For earthquakes with the size less than about 3.0$\times$10$^{21}$dyne-cm(nearly same as M$_{L}$=3.7), the stress drop tends to decrease with the decreasing moment. This fact suggests a breakdown of scaling law of source parameters below the threshold magnitude. The moment magnitudes calculated from source parameters appear to be slightly larger than the Richter's local magnitudes in the range above M$_{L}$=3.5.3.5.

• The Journal of Korea Robotics Society
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• v.8 no.1
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• pp.43-50
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• 2013

$A^*$ algorithm is a global path generation algorithm, and typically create a path using only the distance information. Therefore along the path, a moving vehicle is usually not be considered by driving characteristics. Deceleration at the corner is one of the driving characteristics of the vehicle. In this paper, considering this characteristic, a new evaluation function based path algorithm is proposed to decrease the number of driving path corner, in order to reduce the driving cost, such as driving time, fuel consumption and so on. Also the potential field method is applied for driving of UGV, which is robust against static and dynamic obstacle environment during following the generated path of the mobile robot under. The driving time and path following test was occurred by experiments based on a pseudo UGV, mobile robot in downscaled UGV's maximum and driving speed in corner. The experiment results were confirmed that the driving time by the proposed algorithm was decreased comparing with the results from $A^*$ algorithm.

• Honam Mathematical Journal
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• v.38 no.3
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• pp.661-674
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• 2016

In [15] they introduced a new finite element method for accurate numerical solutions of Poisson equations with corner singularities, which is useful for the problem with known stress intensity factor. They consider the Poisson equations with homogeneous Dirichlet boundary condition, compute the finite element solution using standard FEM and use the extraction formula to compute the stress intensity factor, then they pose a PDE with a regular solution by imposing the nonhomogeneous boundary condition using the computed stress intensity factor, which converges with optimal speed. From the solution we could get accurate solution just by adding the singular part. This approach works for the case when we have the accurate stress intensity factor. In this paper we consider Poisson equations with mixed boundary conditions and show the method depends the accrucy of the stress intensity factor by considering two algorithms.

• East Asian mathematical journal
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• v.34 no.5
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• pp.623-632
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• 2018

In [7, 8] they introduced a new finite element method for accurate numerical solutions of Poisson equations with corner singularities. They consider the Poisson equations with homogeneous boundary conditions, compute the finite element solutions using standard FEM and use the extraction formula to compute the stress intensity factor(s), then they posed new PDE with a regular solution by imposing the nonhomogeneous boundary condition using the computed stress intensity factor(s), which converges with optimal speed. From the solution they could get an accurate solution just by adding the singular part. Their algorithm involves an iteration and the iteration number depends on the acuracy of stress intensity factors, which is usually obtained by extraction formula which use the finite element solutions computed by standard Finite Element Method. In this paper we investigate the dependence of the iteration number on the convergence of stress intensity factors and give a way to reduce the iteration number, together with some numerical experiments.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.755-759
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• 2004

The van Cittert-Zernike theorem has been used in radio astronomy. Recently, the van Cittert-Zernike theorem has been tried to 3D source reconstruction. A couple of interferometer has been used in 3D coherence imaging like Michelson Stellar Interferometer and Rotational Shearing Interferometer. We propose a new type of interferometer, which is a wavefront folding interferometer with a corner cube. By characteristics of the corner cube, it is capable of measuring both mutual intensity and cross spectral density function, and it is very easy to align and robust to disturbance. We simulate the feasibility of this interferometer setup by simulation of point source reconstruction.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.1213-1218
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• 2007

The brake judder comes from non-uniformities in the tire/wheel assembly caused by mechanical effects such as a brake torque variation (BTV). A disc thickness variation (DTV) related with the kinematic behavior of the disc was investigated a main source of BTV. In this study, a dynamic model with brake corner assembly of full vehicle using MSC.ADAMS was correlated by experiment of judder phenomenon. Judder was generated and correlated systematically by judder experiment in chassis and brake dynamometer from variation in the thickness of the disc. Also it has been found a judder transfer path and variation of the braking pressure. Through analysis of transfer function and movement of subsystem caused by BTV generation, design parameters have been found. Based on the results obtained from parameter study of suspension module, the effective design process and developed model with brake corner assembly was suggested for vibration reduction of steering wheel caused by the judder phenomenon.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.32A no.8
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• pp.107-118
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• 1995

Three-dimensional simulator for thermal oxidation process is developed. The simulator is consisted by two individual module, one is analytic-model module and the other is numerical-model module. The analytic-model which uses simple complementary-error function guarantees fast calculation in prediction of multi-dimensional oxidation process. The numerical-model which is based on boundary element method (BEM), has a good accuracy and suitable for various process conditions. The results of this study show that oxide growth is retarded at the corner of hole structure and enhanced at the corner of island structure. These effects are reson of different distribution of oxidant diffusion and mask stress. The utility of models and simulator developed in this study is demonstrated by using it to predict not only traditional shape of LOCOS but also process effects in small geometry.

• Journal of Korean Medicine Rehabilitation
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• v.25 no.1
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• pp.1-15
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• 2015

Objectives The aim of this study was to investigate the effects of Cannabis Fructus on exercise capacity and cognitive function in chronic hypoperfusion induced vascular dementia rat model. Methods Vascular dementia rat models were induced by chronic cerebral hypoperfusion through bilateral common carotid arteries occlusion (BCCAO). All rats were randomly divided into 4 groups: normal group; control group; CF I group (feeding Cannabis Fructus 100 mg/kg); CF II group (feeding Cannabis Fructus 300 mg/kg). In order to study the effects of oral administration of Cannabis Fructus on vascular dementia rat models, corner turn test, hole board test, radial arm maze test, passive avoidance test were taken and Acetylcholine (ACh) activity, Acetylcholinesterase (AChE) activity, serum of Vascular endothelial growth factor (VEGF) protein level were measured. Also histological findings of the liver, kidney, brain and the change of Tau immunoreactive neurons in hippocampus were observed. Results CF I and CF II showed significant improvement in corner turn test, hole board test, radial arm maze test, passive avoidance test, Acetylcholine (ACh) activity, Acetylcholinesterase (AChE) activity, the serum of Vascular endothelial growth factor (VEGF) protein level and the change of Tau immunoreactive neurons in hippocampus. CF I showed more significant effect than CF II in these tests. However in histological observations of the liver and kidney both CF I and CF II showed glomerular injury and hepatotoxicity. Conclusions These results suggest that Cannabis Fructus was helpful in improving exercise capacity and cognitive function on Chronic hypoperfusion induced Vascular Dementia rats. However Cannabis Fructus affects the liver and kidney, therefore suggest that this is an area for further study.

• Korean Journal of Remote Sensing
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• v.27 no.1
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• pp.33-41
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• 2011

In the information communication technology, it is world-widely apparent that trend movement from internet web to smartphone app by users demand and developers environment. So it needs kinds of appropriate technological responses from geo-spatial domain regarding this trend. However, most cases in the smartphone app are the map service and location recognition service, and uses of geo-spatial contents are somewhat on the limited level or on the prototype developing stage. In this study, app for extraction of corner point features using geo-spatial imagery and their linkage to database system are developed. Corner extraction is based on Harris algorithm, and all processing modules in database server, application server, and client interface composing app are designed and implemented based on open source. Extracted corner points are applied LOD(Level of Details) process to optimize on display panel. Additional useful function is provided that geo-spatial imagery can be superimposed with the digital map in the same area. It is expected that this app can be utilized to automatic establishment of POI (Point of Interests) or point-based land change detection purposes.